The invention relates to a method to detect whether a parked motor vehicle has been hit, i.e. whether a collision has occurred, and/or whether the motor vehicle has been moved by external influence. In particular, the method is provided for detection of a collision, when the motor vehicle is shut down, i.e. when the motor vehicle is in an ignition-off condition, i.e. the ignition system is switched off, which can be detected, for example, at terminal 15 off-state according to DIN (German Industrial Standard) 72552.
DE 10 2009 039 913 A1 is known in the art for this purpose to switch off a high-voltage system in a motor vehicle, when the motor vehicle is hit as a traction battery of the high-voltage system is charged. The sensor is hereby based on an acceleration detection. The use of the existing crash sensor for deploying an airbag is not possible with this system since its acceleration sensor is not sensitive enough to detect a collision for switching off a high-voltage system. The motor vehicle is, therefore, provided with a sensor and a control unit, which are used exclusively for switching off the high-voltage system. A disadvantage of this system is the need for providing a dedicated circuitry, causing added production costs for the motor vehicle.
EP 2362362 A1 discloses a method for charging electric vehicles in geographically dispersed charging stations. The charging operation of a motor vehicle is hereby monitored in the charging station, and an image of the motor vehicle is recorded in the charging station, when the charging process is interrupted, interfered with, or deviates from a given course. This increases security against abuse and manipulation. An interference during the charging process is detected on the basis of a predetermined charging characteristic.
A disadvantage of this system is that a collision of the motor vehicle with an object hitting it does not necessarily interfere with the charging process in of itself, but causes damage, for example, only to a DC link of the high-voltage system. In other words, a collision cannot be detected with the system.
A collision detection when a motor vehicle is at a standstill affords, in addition to the emergency shutdown of a high-voltage system, also other advantages. For example, an airbag can be reliably deployed.